1. Field of Invention
The present invention relates to an illumination apparatus and, in particular, to an illumination apparatus without a light guiding plate.
2. Related Art
In industrial countries, the illuminations consume a remarkable ratio in the entire electricity consumption. According to some researches, in the top 5 industrial countries, the illuminations consume 15% or more of the entire electricity consumption. Based on the potential threat of limited petroleum deposit, the devices with low power consumption have become the most popular products and the most important developing trend.
In order to minimize the electricity wasted in illumination, the illumination lamps with lower power consumption are developed. Currently, the most popular illumination lamps with lower power consumption are definitely LED lamps, which have the advantages of low power consumption, low public pollution, long lifetime, high safety, short lighting response, and small size.
The flat lamp is light and decorative and has a uniform and large lighting surface, so it is a popular choice among the existing illumination lamps. The conventional flat lamp has a structure similar to the backlight module of a display apparatus, which includes a light guiding plate. The function of the light guiding plate is to guide and transmit the emitted light. In more detailed, the light enters the input surface of the light guiding plate, and is then transmitted within the light guiding plate by total reflection. Finally, the light is emitted through an output surface of the light guiding plate so as to generate a uniform output light.
However, since the light has been reflected for many times, the energy of the light is lost so as to decrease the light extraction efficiency (about 60-65%). Besides, the additionally arranged light guiding plate may increase the weight of the flat lamp as well as the cost thereof.
Therefore, it is an important subject of the present invention to provide an illumination apparatus with lower cost, higher light extraction efficiency and better light output uniformity.